


Quantum Physics seems easier than this

by RedPineTrees



Category: Undertale (Video Game)
Genre: Agender Character, Fluff, Gen, Post-Canon, Puberty
Language: English
Status: Completed
Published: 2015-10-26
Updated: 2015-10-26
Packaged: 2018-04-28 04:32:14
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,399
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5077921
Author URL: https://archiveofourown.org/users/RedPineTrees/pseuds/RedPineTrees
Summary: <blockquote class="userstuff">
              <p>After the events of the pacifist ending, Frisk and Toriel live together, Toriel acting as their mother. Though, since Frisk is only a child, they face some interesting events as they get older.</p>
            </blockquote>





	Quantum Physics seems easier than this

**Author's Note:**

> PLEASE READ:  
> In this fic, my headcanon Frisk starts the game at about 10 years old. While they are agender, I headcanon for them to be designated female at birth. This work does contain talk and light description of periods (there will be mention of blood) and if this upsets you, please exit out. This was an idea I came up with randomly one day, and I wrote it down without having anyone beta it. There are bound to be grammar or spelling mistakes. Honestly, this isn't one of my greatest works. This is my first time writing for Undertale, and I will gladly write for it again.

I had always wanted to be two things; a teacher, and a mother.  
Fortunately, after we reached the surface and got in to the groove of our lives, I was able to become both. A teacher to my community, and a mother to Frisk, the human child who made our lives better than they ever could have been. Though they were fiercely independent in their own ways, there were many times where they needed guidance, or just someone to be there for them. Of course, I tried to do my best, supporting them in their choices more often than not. 

From one of our many conversations, I learned that Frisk was ten years old, which surprised me. They seemed wise beyond their years, and when I expressed this thought to Sans, his smile faded.  
“You have no idea, Tori. That kid, they've been through a lot.” He said quietly, his white pupils gone from his eyes.  
“What do you mean?” I asked, blinking in surprise at his sudden change in tone. It was unlike him to be so serious when talking about Frisk.  
“I couldn't explain it even if I tried, to be honest with you. Don't ask them either, it's. . . Not something to be brought up. Ever. Got it?” He looked up at me, more serious than I had ever seen him. While startled, I knew that if Sans was serious about something, it was an important matter.  
“Alright. I understand, don't worry.” I smiled at him. “By the way, Sans. I've been wanting to tell you about a book I've been reading!” He returned to his normal state, his usual smile returning. I gave a small inward sigh of relief, glad that I hadn't completely put a damper on the mood.  
“Oh yeah? What's it about?”  
“Anti-gravity! I haven't been able to put it down!” 

Besides the awkward conversation with Sans, after finding out that Frisk was ten years old, I decided to start reading on the development of humans. Despite being a humanoid type of person, I was still a monster, and I had no idea what humans went through when they underwent puberty. I went to the internet in search of answers, and realized something. 

I did not know what reproductive organs Frisk had. Now, that would be an awkward question to ask a ten year old, but it had to be done. I decided that I would ask after dinner one night.  
“Frisk..” I began, looking over to where they were reading on the couch.  
“Mm.”  
“Do you have a penis or a vagina?” I asked bluntly.  
“What.” They stared at me. It was blank, though there were hints of annoyance in their expression. For being so young, they understood plenty about gender, and they personally identified with agender.  
“I need to know. You are a growing human, and I need to know how to prepare for your puberty.” I explained, feeling uneasy as they continued to stare at me.  
“. . . I was born with a vagina.” They replied, now furrowing their brow. “You won't tell the others, right? I don't want to be thought of any different.”  
“Of course I won't tell anyone else! As far as they are all concerned, you are the human child we know and love, as mysterious as the day we met you.” I told them, sitting beside them. They sighed, turning to the next page in their book (Quantum Physics for Dummies) and attached themselves to my side.  
“Good. I want to keep it that way.”

Their eleventh birthday came and went without incident, though when Frisk was more irritable than usual I would wonder silently to myself, when would their period come? I had already prepared for the day, knowing it could happen at any time from the ages of ten to fourteen, and had a box under my bed ready with anything non perishable they might need. It was one day near Christmas, they came to me not needing help with a period, but rather, a literal growing issue.  
“You researched on humans, right Tori?” They asked while we decorated our Christmas tree.  
“I did indeed! Do you have a question for me?”  
“Yes. I read a book that said my chest is going to get bigger when I get older. Is that true?” I stopped what I was doing, craning my head around the tree to see Frisk decorating away, finding it to be a normal question.  
“Uh... Yes! Yes, people born with vaginas usually develop more breast tissue as they get older.” I replied, picking up the next ornament I wanted to place.  
“Then I want a sports bra for Christmas. So I can get used to what wearing a binder will be like.” Frisk said. I had researched binders before, having read about them in an article about agender people, and wasn't surprised that Frisk knew what they were. They were a curious child, and researched on many things that made them curious by using the wonderful internet.  
“Alright! Then I will put that on the list of things to get you. Have you come up with any other ideas? A list I could give the others so they know what to get you?”  
“No. I want them to get me something they think I would like, not something I've told them to get. The sports bra is an exception. . . What about you? What do you want for Christmas?”

Christmas came and went. They grew a few inches taller, and after the holiday season, I took them to buy better fitting clothing. 

The day of their twelfth birthday, which just so happened to be a Saturday, they were curled up in bed past nine o'clock in the morning. They had told me they weren't feeling well the night before, but I didn't expect to go and check on them, only to see a large red blotch on their blanket. Frisk was still asleep, but the red was there, plain as day. I covered my mouth, panicking. I thought I was prepared, but I was definitely not emotionally prepared. How did I even handle this? Was there some sort of talk I needed to give Frisk? Did I need to take them to the doctor after this to make sure everything was functioning properly? How much exactly were they supposed to bleed? 

While I internally screamed, Frisk began to wake up, squinting from the sunlight that streamed into their room. They frowned when they saw me, obviously worried because of my own expression, until they looked down. Frisk then gave the most frustrated “UGH” sound before pushing the blanket off their body, their frown increasing as they glared at their stained pajama bottoms.  
“Did you ever google how to remove blood stains?” Frisk asked, now looking at me. Finding my voice, I quickly replied.  
“Oh! Yes, um, a mixture hydrogen peroxide and water should work. . . Do you need me to do anything for you?? I will clean your bedding and pajamas!”  
“I think I can manage. Do you have anything for me to use?”  
“Yes! Under my bed, there's a box marked for this occasion. Do you want me to cancel the party for this afternoon?”  
“No. New theme.”

They explained to me as they shed their soiled clothing that the theme of the party should be changed to a pajama party. Everyone wear their comfortable bed clothing and relax while watching what Alphys called “anime”. I had already prepared a cake, and I had learned that humans had something called “take out” where you could place a food order and they brought it to your door. Occasionally, Frisk and I did that on nights where we didn't feel like cooking. This plan seemed excellent, so while I began soaking their clothes in the mixture of peroxide and water, I called our different friends, telling them of the change in plans. 

I was pleasantly surprised when I hung up the phone with Sans to find Frisk hugging my side, fresh from the shower they had taken to clean up.  
“Mom?” They said softly, in to my robes.  
“Yes, my child?” I responded, gently picking them up to rest them on my hip.  
“Thank you. For everything. I don't say that enough.”  
“The pleasure is all mine. I only want to do what makes you happiest, and I try my best.”  
“You are the best.”

**Author's Note:**

> Thank you for reading my first Undertale fic! I know this isn't the greatest fic ever, but I liked the idea, and wanted to post it and see if anyone would want me to put more effort into possibly a series of fics where Toriel helps Frisk through the wonders that is puberty.  
> By the way: Frisk being DFAB is just my headcanon. If you have an issue with it, please don't comment about it. There was a warning at the beginning. You should have not read this if you didn't like DFAB Frisk Headcanons.  
> To those of you who did like this: Thank you!! I appreciate your support.


End file.
